A small-size camera unit mounted in a mobile phone includes a lens driving mechanism for moving a lens, in order to realize an autofocus function and the like. As the lens driving mechanism for use in such a small-size camera unit, recently, a lens driving mechanism using a so-called bimetallic actuator has been developed. The bimetallic actuator has two metal layers having different coefficients of thermal expansion. By heating, the two metal layers are expanded with their amounts of expansion being different from each other, so that a free end is displaced relative to a fixed end.
The bimetallic actuator has a simple structure, and therefore can be easily downsized and thinned, and additionally a relatively large amount of displacement and a relatively large generated force can be obtained. Particularly, in a small-size bimetallic actuator, power consumption can be suppressed low, too. Thus, there is a great advantage of using the bimetallic actuator in a small size lens driving mechanism.
Conventional techniques for moving a lens of an optical apparatus by using the bimetallic actuator are disclosed in Patent Documents 1 and 2, for example.